In some cases, an ailment may affect the quality of a patient's sleep. For example, neurological disorders may cause a patient to have difficulty falling asleep, and may disturb the patient's sleep, e.g., cause the patient to wake. Further, neurological disorders may cause the patient to have difficulty achieving deeper sleep states, such as one or more of the nonrapid eye movement (NREM) sleep states.
Epilepsy is an example of a neurological disorder that may affect sleep quality. In some patients, epileptic seizures may be triggered by sleep or transitions between the sleep states, and may occur more frequently during sleep. Furthermore, the occurrence of seizures may disturb sleep, e.g., wake the patient. Often, epilepsy patients are unaware of the seizures that occur while they sleep, and suffer from the effects of disturbed sleep, such as daytime fatigue and concentration problems, without ever knowing why.
Other neurological disorders that may negatively affect patient sleep quality include movement disorders, such as tremor, Parkinson's disease, multiple sclerosis, or spasticity. The uncontrolled movements associated with such movement disorders may cause a patient to have difficulty falling asleep, disturb the patient's sleep, or cause the patient to have difficulty achieving deeper sleep states. Psychological disorders, such as depression, mania, bipolar disorder, or obsessive-compulsive disorder, may also similarly affect the ability of a patient to sleep, or at least experience quality sleep. In the case of depression, a patient may “sleep” for long periods of the day, but the sleep is not restful, e.g., includes excessive disturbances and does not include deeper, more restful sleep states. Further, chronic pain, whether of neurological origin or not, as well as congestive heart failure, gastrointestinal disorders and incontinence, may disturb sleep or otherwise affect sleep quality.
Drugs are often used to treat neurological disorders. In some cases, neurological disorders are treated via an implantable medical device (IMD), such as an implantable stimulator or drug delivery device. The treatments for neurological orders may themselves affect sleep quality.
Further, in some cases, poor sleep quality may increase the symptoms experienced by a patient due to a neurological disorder. For example, poor sleep quality has been linked to increased pain symptoms in chronic pain patients and increased seizure activity in epileptic patients, and may also result in increased movement disorder symptoms in movement disorder patients. Further, poor sleep quality may exacerbate many psychological disorders, such as depression. The link between poor sleep quality and increased symptoms is not limited to ailments that negatively impact sleep quality, such as those listed above. Nonetheless, the condition of a patient with such an ailment may progressively worsen when symptoms disturb sleep quality, which in turn increases the frequency and/or intensity of symptoms.